When is friable asbestos typically encountered?

Friable asbestos is typically encountered in materials that can be easily reduced to a powder by hand pressure. This characteristic is significant because friable asbestos has a high potential for releasing fibers into the air when disturbed, posing health risks associated with asbestos exposure. Materials that are classified as friable include those that are soft and can crumble or break apart easily, such as insulation materials, spray-applied fireproofing, and some types of acoustic ceiling tiles.

The other choices do not accurately describe the nature of friable asbestos. Heavy machinery may contain asbestos but is not specifically indicative of friability, as components are often structurally solid rather than easily crumbled. Roofing tiles, while they may contain asbestos, are typically not considered friable due to their rigidity. Lastly, biodegradable materials do not relate to asbestos and would not typically contain this hazardous substance. Therefore, that choice does not apply in the context of asbestos identification.